Various embodiments of a method of producing dried cellulose nanofibrils are described herein. In particular, the embodiments described herein relate to an improved method of producing dried cellulose nanofibrils.
Cellulose nanoscale products, such as cellulose nanofibrils (CNF), nano-fibrillated cellulose (NFC), and cellulose nano-crystals (CNC) may be produced from mechanical or chemo-biological processing. Because of the processing methods, all the intermediate cellulose products exist in aqueous medium, which requires additional processes for production of dry products. Dehydrolysis of wet cellulose products poses a challenge since a number of hydroxyls from cellulose contribute to hydrophilicity that holds together water molecules, as well as other cellulose chains. Drying cellulose affects the final dimensions of cellulose crystals and fibrils due to the aggregation of individual fibrils. The cellulose fibrils or crystals in CNF, NFC, and CNC agglomerate with other fibrils or crystals as water is removed from the aqueous medium in drying processes such as freeze drying, critical point drying, spray drying, oven drying, and air drying.
It is desirable to provide an improved method of drying an aqueous suspension of cellulose nanofibrils to produce dry cellulose nanofibrils that may be used in non-aqueous applications, such as in non-polar polymer matrices used in forming non-polar polymer composites.